Gravitational potential energy:

$\overline{){{\mathbf{U}}}_{{\mathbf{g}}}{\mathbf{=}}{\mathbf{m}}{\mathbf{g}}{\mathbf{h}}}$

Kinetic energy:

$\overline{){\mathbf{K}}{\mathbf{E}}{\mathbf{=}}\frac{\mathbf{1}}{\mathbf{2}}{\mathbf{m}}{{\mathbf{v}}}^{{\mathbf{2}}}}$

Elastic potential energy for a stretched cord/spring:

$\overline{){{\mathbf{U}}}_{{\mathbf{e}}}{\mathbf{=}}\frac{\mathbf{1}}{\mathbf{2}}{\mathbf{k}}{{\mathbf{x}}}^{{\mathbf{2}}}}$

The kinetic energy and gravitational potential energy of the system are mainly due to Lona's mass. The bungee cord provides the elastic potential energy of the system.

The system is stationary (v = 0). Thus, their kinetic energy is zero.

Your adventurous friend Lola goes bungee jumping. She leaps from a bridge that is 100 m above a river. Her bungee cord has an un-stretched length of 50 m and a spring constant k = 600 N/m. Lola has a mass of 48 kg.

Lola stretches the bungee cord and it brings her to a stop. She then bounces back up again. What type(s) mechanical energy does the system (Lola and the bungee cord) have just before she jumps? (i.e., gravitational PE, elastic PE, kinetic energy, etc.)

Frequently Asked Questions

What scientific concept do you need to know in order to solve this problem?

Our tutors have indicated that to solve this problem you will need to apply the Equations for Energy Conservation concept. If you need more Equations for Energy Conservation practice, you can also practice Equations for Energy Conservation practice problems.